The breakdown: The biggest offseason changes for the Vikings are here along the defensive line. And for now, it’s a position of uncertainty. Gone are longtime stalwarts Kevin Williams and Jared Allen. Williams recently signed with the Seattle Seahawks after 11 standout seasons in Minnesota. Allen has traded spots within the division, signing with the Chicago Bears. Both are likely missed more in name value and locker-room influence than on-field production. Williams and Allen still had their moments last year, but didn’t provide the same down-to-down, game-to-game impact as a few years earlier.

In their place, the Vikings made sweeping changes, signing three NFL veterans and drafting two players. Joseph is the biggest addition, a true nose tackle for new coach Mike Zimmer’s defense. Letroy Guion was never a real fit at nose tackle and Minnesota seemed to make due. Joseph, 25, is a big body at 6-foot-4 and 323 pounds and can occupy blockers and even add disruption by penetrating the line.

Griffen, with a new, big, five-year contract, takes over Allen’s spot on the right side as the blind-side rusher to right-handed quarterbacks. Griffen has a lot of potential as a quick-twitch speed rusher and he’s shown ability in glimpses with 13.5 sacks the past two seasons as a situational pass-rusher, sometimes even coming from the interior of the line. He’ll be asked to take another big step after getting paid and getting a starting spot.

Robison returns as the steady veteran and is now the leader of the line as the most experienced player and the elder statesman at 31. Robison has had between eight and nine sacks each of the last three seasons. Floyd likely takes the place of Williams as the 3-technique and will need to show why he was selected as the first of the team’s three first-round draft picks last year. Floyd has the size, strength and athletic ability to be a force, and Zimmer’s defenses have featured quality play from the position, such as Geno Atkins in Cincinnati.

The Vikings signed Wootton, an end, and Johnson, a tackle, to provide experienced backups, as Zimmer plans on using a rotational system. Wootton, 27, will be looking to re-establish his value on a one-year deal after dipping to three sacks last year with Chicago as a full-time starter. Johnson, 29, is on a one-year deal, as well, and has played 40 games over the past three seasons. Evans likely returns for another year as a backup nose tackle and provides depth, experience and steady play in the role.

Minnesota used a third-round draft pick on Crichton this year out of Oregon State. He’s a high-motor player who can rush the passer and hold his ground in run defense. Stephen, a seventh-rounder, might be a sneaky addition as a 6-foot-5, 310-pound tackle who can move well.

Best position battle: The starting four are likely set, though Floyd might have to prove he’s ready to take the next step. Zimmer will also use a rotation, and the team has depth. Johnson, Evans or Stephen might be able to test Floyd for the final starting spot, but likely the biggest competition will be for the final one or two spots, depending upon how many defensive linemen the Vikings keep.

Going into training camp, it would seem as if the top eight spots are accounted for, unless some of the younger players really challenge and knock off a player like Johnson. Minnesota has to be intrigued with Stephen, who was even taking some second-team reps during minicamp, though Joseph wasn’t practicing and the coaches were using quite an assortment of players rotating in and out.

That would likely leave one spot left for Stephen and the other young players to battle for. Stephen has the upside and equity of being a draft pick this year. Baker has been around two years and even saw time in five games last year after injuries hit. Faciane, an undrafted rookie, was also seeing some second-team time during minicamp. Trattou is a long, lean end who the team signed last year from the New York Giants and he played in one game. Kheeston Randall was a January signing, having spent time with Zimmer in Cincinnati last year.

Ranking against the rest of the NFC North: 1. Lions; 2. Vikings; 3. Bears; 4. Packers. One of the most interesting storylines in the division this year was the swapping of teams by a few prominent pass rushers. Allen went to Chicago as part of its defensive line makeover. Wootton traded spots with Allen, even though he’s likely looking at a backup spot after starting for the Bears the past two seasons.

Former Chicago end Julius Peppers went to Green Bay and is making a slight change as a standup outside linebacker in the Packers’ 3-4 defense. The Bears signed former Detroit end Willie Young. Even Guion found a home in the division, signing with Green Bay

The Packers are the only team in the division to run a 3-4 system and the three members of their line might be the biggest question marks. B.J. Raji returns in the middle after a down season. Mike Daniels will become a full-time starter off a 6.5-sack season.

The other side will likely be manned by Datone Jones, a first-round draft pick last year who struggled to make an impact. The positional weakness hasn’t been without effort on Green Bay’s part. The Packers drafted Jones last year and Jerel Worthy as a second-rounder in 2012.

Detroit isn’t lacking for potential. Led by Ndamukong Suh, the Lions line features four potential impact starters. Consistency has never been Detroit’s calling card, though. Suh can be one of the league’s most dominating defensive tackles and his game might be steadier than he’s given credit for. He can stand up against the run and also get to the quarterback from the middle. He slipped to 5.5 sacks last season after eight the previous season and 10 in his rookie season in in 2010, but still had another solid all-around season.

Nick Fairley, a 2011 first-rounder, looked like he was really coming along last year starting next to Suh inside. He will be a free agent after next season after the team didn’t pick up the option for a fifth year. He’ll have motivation and incentive to have a big year. Ziggy Ansah had eight sacks as a rookie last year after being selected in the first round and should only continue to develop as a player, not having much experience playing the game as a native of Ghana. Jason Jones should return after missing all but three games last year with a patellar tendon injury to start at the other end.

A year after completely remaking its offensive line, Chicago did the same thing to the defensive line this offseason. Allen, 32, might be the biggest addition for the Bears, but might not be the best. The team added Lamarr Houston, 27, from the Oakland Raiders, who had five sacks last season. Houston is a 302-pounder who can play inside or out and is slated to start on the opposite end from Allen.

Jay Ratliff started four games after Chicago signed him midway through last season when he was cut by the Dallas Cowboys because of injuries. If healthy, Ratliff might be able to show the talent that made him a four-time Pro Bowl pick in Dallas. Stephen Paea returns to the Bears’ line, but Chicago also drafted Ego Ferguson (second round) and Will Sutton (third round) in May.